This invention relates generally to the treatment of waste materials and more particularly, though not exclusively, to the treatment of organic waste material such as for example, sewage sludge.
One particular application of the present invention relates to the treatment of organic waste materials by the use of worm species. This process is referred to hereinafter as vermiculture. Vermiculture is a process by which organic material is fed to a variety of worm species with the purpose of converting the organic material into increased worm biomass and vermicast. Vermicast is the excreter from worms and has use as a plant growth medium and soil conditioner. The worm biomass can be used for bait, animal feed and domestic and small composting systems. Worms have the ability to convert a wide range of organic material including sewage sludge provided the material is presented in an acceptable form. Vermiculture has been used in the past for the stabilization of sewage sludge and other organic waste however, previous systems have been on a small scale and not be considered economically viable.
It is an object according to one aspect of the invention to provide apparatus suitable for use in vermiculture processing which enables large scale treatment of waste materials.
According to one aspect of the present invention there is provided apparatus suitable for use in the treatment of waste and/or organic materials, the apparatus including a main body having a treatment chamber therein which includes a base which when the apparatus is in a harvesting mode is arranged with a space therebelow, the base including a plurality of generally parallel spaced apart support elements, the support elements being spaced apart at a distance sufficient to support the material within the chamber during the treatment process and enable extraction of the treated material through the spaces between the support elements during a harvesting process.
Preferably, the treatment chamber is at least partially bounded by a side wall and the support elements extend across the chamber between opposed sections of the side wall thereby defining the spaces between adjacent support elements.
Preferably, the base includes openings at the opposed sections of the side wall, each opening being associated with and generally aligned with a respective one of the spaces between adjacent support elements, the openings extending from the support elements in the direction of the side wall. It will be appreciated that the support elements may extend longitudinally of the main body.
Preferably, the space between the elements, centre to center, is about from 50 mm to 100 mm, more preferably, from 70 or 80 mm to 90 mm and even more preferably from 85 mm to 90 mm.
The support elements may be in the form of elongated bars or rods which may be about 12 mm in cross-sectional dimension. The support elements are preferably of formed metal and more preferably steel, such as for example, 500 mpa yield strength steel.
In one preferred form of the invention, the support elements are in the form of substantially U-shaped rods or bars, the spaces between the uprightly directed arms of each U-shaped element defining the openings referred to earlier.
The main body may be in the form of a generally box like structure which is preferably of a general rectangularly or square shape when viewed in plan and has an open top. The apparatus may include a plurality of such structures in the form of modular units which can be arranged side by side. The support bars may extend laterally across the main body or extend longitudinally with the support bars in each modular unit being substantially aligned. In one preferred form, the main body may be carried on support legs so that the base thereof is raised above the ground or other support surface to define the space below the base. The side walls may, for example, be formed of a mesh material or be solid. The apparatus may further include a spray assembly disposed above or to the side of the main body for selective spraying of the waste material within the treatment chamber. There may further be provided covers or a roof structure which can overlie the main body.
According to another preferred form of the invention, the main body forms a unit and the apparatus includes a plurality of units disposed in spaced apart planes one above the other. Preferably, there is a plurality of units disposed in each plane.
In this multi-tier form of the invention, the apparatus may include a support frame which includes one or more support columns. In one arrangement, each unit may be mounted to the or each support column in cantilevered fashion. In another arrangement, each unit may be mounted to at least two support columns at opposite ends thereof. Preferably, there is further provided a track assembly operatively connected to the support frame and being adapted to receive a harvesting device thereon.
According to another embodiment the main body is in the form of a basket unit there being provided a plurality of units disposed one above the other. The apparatus further includes a mobile platform which is movable into a position whereby one of the basket units can be transferred onto the platform, the platform being movable to a position where the material within the basket can be harvested.
The apparatus of the present invention enables a continuous treatment and harvesting process to be effected. Waste material is fed to the treatment chamber through the open top. The upper section of the chamber forms a feed zone and the intermediate section of the chamber forms a treatment zone and the lower section forms a harvesting zone. The worms within the chamber progressively stabilise the material. The space beneath the base forms a harvest collecting zone, the material from the chamber being extracted through the base.
A second aspect of the present invention is related to a harvesting device which is suitable for use with the apparatus described above. Yet another aspect of the present invention relates to components suitable for use in the harvesting apparatus.
According to another aspect of the present invention there is provided a harvesting device which is suitable for use with the treatment apparatus described above. The harvesting device includes a carriage which is adapted to move within the space below the base of the main body and in a direction generally parallel with the support elements of the base, and a harvesting tool which includes a plurality of extraction elements which project outwardly, the arrangement being such that when in use the extraction elements are adapted to extend through the spaces between the support elements into the treatment chamber so as to dislodge and extract the material through the base.
In one preferred embodiment, the tool is mounted for rotation on the carriage about an axis of rotation which extends transversely.
In one preferred form, the tool includes an elongated rotor body mounted for rotation about its longitudinal axis. The rotor body may be generally circular in cross section and may be in the form of a cylinder or drum. Preferably, the extraction elements are arranged to extend generally radially of the outer surface of the rotor body. By radially is meant that the extraction elements project outwardly from the outer surface of the rotor body. The elements do not necessarily extend exactly radially in the mathematical sense and may for example, be inclined to the true radial axis.
In one form of the invention, the extraction elements comprise a series of blades each having a radially projecting arm section and a laterally extending blade section at the free end of each arm. The blade section may be dimensioned so that it is adapted to fit between the openings between adjacent support elements in the base of the apparatus.
In another form of the invention, the extraction element may comprise tines which extend generally radially of the outer surface of the rotor element of the tool.
In yet another form of the invention, the extraction elements may include a plurality of blades or tines at least some having associated therewith a radially extending brush element.
The harvesting tool need not necessarily be rotatable. For example, the tool may include a plurality of extraction elements in the form of blades mounted on a frame or carriage which is adapted to move beneath the base of the main body with the blades extending into the treatment chamber via the spaces between the support elements in the base.
In one preferred form of the invention the extraction elements are arranged in one or more groups with the elements in the or each group being spaced apart from one another and extending across the rotor body from one side to the other. In one preferred form, two groups of elements are provided with associated elements in each group being opposite to one another. The elements in each group may be arranged in a spiral configuration from one side of the rotor body to the other.
The harvesting device may further include a base upon which the carriage can move. The base may include a track section for the carriage and wheels for moving the base between a harvesting position and a delivery position in which material collected is transferred to a storage location. In another form the carriage may be operatively mounted to the main body such as for example, on a rail for movement and/or guidance relative thereto.
Drive means may be provided for moving the carriage along the base. Such drive means may include a drive motor for driving a rope or cable drum which is operatively connected to the base.
In another preferred form, the tool includes a plurality of extraction elements in the form of blades mounted on a frame or carriage which is adapted to move beneath the base of the main body with the blades extending into the treatment chamber via the spaces between the support elements in the base.
Preferably, the extraction elements are arranged in one or more groups with the elements in the or each group being spaced apart from one another and extending across the rotor body from one side to the other with two groups of elements are provided with associated elements in each group being opposite to one another, the elements in each group being arranged in a spiral configuration from one side of the rotor body to the other.
The device may further include a base upon which the carriage can move, the base including a track section for the carriage and wheels for moving the base between a harvesting position and a delivery position in which material collected is transferred to a storage location.
In yet another embodiment the carriage includes a frame which is adapted to be operatively connectable to a vehicle so that it can be raised or lowered and positioned within the space below the base of the main body of the apparatus, the tool including a plurality of blades at one end of the frame.
In yet another embodiment the device includes a main frame, wheels on the main frame which are adapted to run on tracks positioned relative to the main body of the apparatus so that the harvesting device can move beneath the base of the main body. The harvesting tool is operatively connected to the main frame, and a collecting receptacle is operatively connected to the main frame the receptacle having an open top side.
Preferably, the harvesting tool is disposed above the receptacle and movable relative thereto.
There are several types of harvesting devices described. It will be appreciated that the various forms of harvesting tool can be used on the various types of harvesting device. For example, the type of device which is operatively connectable to a vehicle can have a rotatable cutter thereon.
Preferably, the collecting receptacle includes a base which includes a conveyor means for discharging the harvested material from the receptacle. Preferably there is also provided a filling device for filling the treatment chamber, the filling device including a receptacle operatively connected to the main frame having an open top and a base, the base including conveying means for feeding material to a selected treatment chamber. It will be appreciated that the filling device may be completely separate from the harvesting device and operable totally independent thereof. This separate filling device may constitute a further distinct aspect of the invention.